Tun-Linn et al. (2015) studied the bioavailability of NO in blood vessels of DHF patients in Singapore and found that significant increases in NO can be used as a predictor of DHF. However, the results of Trairatvorakul et al. (2005) in Thailand contrast with those findings – the serum NO level in DF patients was significantly lower than that in normal controls. In predicting DHF, the levels of vascular endothelial growth factor (VEGF) or its receptors were also inconsistent with those found in the study in Thailand (Conroy et al., 2015). The gene discussed is VEGFA; the disease is Dengue hemorrhagic fever.